Generally, integrated circuits (IC) in semiconductor chips include both active components such as operational amplifiers, and passive components such as resistors (i.e., R components) and capacitors (i.e., C components). Passive components (i.e., resistors and capacitors) typically have relatively large process (i.e., fabrication) variations with changes in the operational parameters of a device. For example, an analog RC low-pass filter circuit (IC) may be implemented using a typical submicron CMOS process, and may exhibit large variations in cutoff frequency behavior.
To compensate for the process variations in passive components (i.e., resistors and capacitors), adjustments may be made in the fabricated chip, such as with electric fuses, laser trimming, or other techniques; however, these adjustments can be relatively costly. A lower cost alternative is to use a dedicated calibration circuit together with the RC circuit (e.g., a RC low-pass filter circuit) to reduce the process variations in the RC circuit, by tuning the measured RC time constant of the calibration circuit and thus the cutoff frequency of the RC circuit close to a given target value.